Conventional tire designs utilize treads with circumferentially and laterally extending grooves that divide the tire tread into a plurality of block elements. The grooves expel water from beneath the tread to prevent hydroplaning and also to provide improved traction in snow, mud, and wet road conditions. In some designs, however, small tread blocks can reduce tire stiffness, thereby affecting performance and causing irregular wear of the tread. One solution to this problem has been to reinforce small tread blocks by connecting them to adjacent tread blocks with tie bars. The tie bars are typically formed in the bottom of the groove and do not extend all the way to the top of the tread blocks.
While tie bars help to improve handling and reduce irregular wear, the location of tie bars in the bottoms of the grooves does not provide optimal performance. Specifically, this tie bar configuration does not reinforce the upper ends of the tread blocks where it is needed, and thereby provides only a limited increase in stiffness when the tire is new. Having tie bars in the bottoms of the grooves also tends to cause excessive stiffness of the tread blocks as the tire becomes worn from use. Moreover, the location of tie bars in the bottoms of grooves inhibits the water expelling function of the grooves.
A need therefore exists for an improved tire tread design which overcomes these and other drawbacks of the prior art.